In neurology, many applications of quantitative imaging relate information at corresponding positions in the left and right hemisphere of the brain. Region of Interest (ROI) based comparisons between left and right hemisphere of the brain can play an important role across many imaging modalities and clinical questions. Generally, these applications take advantage of corresponding portions of the left and right hemispheres to, for example, compare the anatomy and make an appropriate diagnosis. These applications reflect locations about the mid-sagittal plane, which divides the left and right hemispheres. Using image analysis techniques, the brain scan is oriented such that the mid-sagittal plane is mapped to a pre-defined position P on the x-axis. Subsequently, corresponding points in the left and right hemisphere are identified via reflecting the x-axis component of a point at P. These applications typically assume that the brain is symmetric with respect to the mid-sagittal plane. However, this assumption is not always true. Rather, regional anatomical asymmetry typically exists across individuals, degrading the power of approaches that assume brain symmetry (mirroring, asymmetry measures). Furthermore, an individual brain is typically not perfectly symmetric but rather, contains normal and abnormal asymmetries. This fact is well known under the term “brain lateralization”. Whereas normal causes of asymmetry include lateralization of brain functionality or just individual cortex anatomy, abnormal asymmetry might also be caused by tumors, stroke, or neurodegenerative diseases.
Standard image analysis techniques attempt to limit individual asymmetry in the brain by deforming the image via a symmetric template based on image registration, commonly denoted as stereo tactical normalization. However, many registration techniques limit the types of deformation that may be completed via parameterization (e.g. b-splines or linear transformations) and are not able to eliminate a brain's asymmetry as the possible deformations do not match the anatomy of a brain. There may be a need for a system that permits the use of quantitative imaging while accounting for variable asymmetries in the brain.